Epilepsy

Chronic neurological disorder characterized by an enduring predisposition to generate epileptic seizures: recurrent, unprovoked seizures resulting from abnormal, excessive, synchronous neuronal electrical activity.

Diagnosis requires ≥2 unprovoked seizures >24 hours apart, OR 1 unprovoked seizure with high recurrence risk (≥60%, e.g., structural lesion, epileptiform EEG), OR diagnosis of an epilepsy syndrome.

Classified by seizure type (ILAE classification):

• Focal seizures: originate in one hemisphere

• Focal aware (no impaired consciousness, formerly "simple partial")

• Focal impaired awareness (formerly "complex partial")

• Focal to bilateral tonic-clonic (secondary generalization)

• Generalized seizures: bilateral network involvement from onset

• Tonic-clonic, absence (typical/atypical), myoclonic, tonic, atonic, clonic

• Unknown onset

Etiology categories: structural (tumor, stroke, trauma, malformation), genetic, infectious (neurocysticercosis, major global cause, TB, HIV-related), metabolic, immune (autoimmune encephalitis), unknown.

Depends on seizure type/focus:

• Focal aware: retained awareness, symptoms depend on cortical area (motor jerking, sensory disturbance, autonomic symptoms, psychic phenomena: déjà vu, fear)

• Focal impaired awareness: altered consciousness, automatisms (lip-smacking, fumbling, wandering), post-ictal confusion

• Generalized tonic-clonic: sudden loss of consciousness, tonic stiffening then clonic jerking, tongue biting (lateral), urinary incontinence, post-ictal drowsiness/confusion lasting minutes-hours

• Absence seizures: brief (<20 sec) staring/behavioral arrest, abrupt onset/offset, no post-ictal confusion, often provoked by hyperventilation: typically childhood onset

• Myoclonic: brief shock like jerks, no loss of consciousness

• Pre-ictal aura (focal onset feature, may indicate seizure focus)

• Post-ictal state: confusion, Todd's paresis (transient focal weakness post-seizure, can mimic stroke), headache, fatigue

• Distinguishing features from syncope: seizures more likely with tongue biting (lateral), prolonged post-ictal confusion, cyanosis during event, incontinence (though seizures and convulsive syncope can overlap in presentation)

Primarily clinical: detailed history from patient AND witness (key, as patient often has no recollection) covering: pre-ictal state, ictal semiology, post-ictal recovery, triggers, duration.

• EEG: supports diagnosis, characterizes epilepsy syndrome, localizes focus: interictal epileptiform discharges support diagnosis but normal EEG does NOT exclude epilepsy (single EEG has ~50% sensitivity); video-EEG monitoring for diagnostic uncertainty (differentiating epileptic vs. non-epileptic/psychogenic seizures)

• MRI brain (structural imaging, preferred over CT): identifies underlying structural cause: hippocampal sclerosis, malformations, tumor, vascular lesions; indicated in most new-onset epilepsy, especially focal-onset

• Bloods: glucose, electrolytes (Na, Ca, Mg), FBC, LFTs, renal function : exclude metabolic provocation; consider toxicology screen

• Lumbar puncture: if infection/encephalitis suspected (fever, meningism, altered consciousness beyond expected post-ictal course)

• ECG: exclude cardiac cause of "seizure-like" event (long QT, arrhythmia): important in convulsive syncope differentiation

• Prolactin: transient rise post-generalized tonic-clonic seizure can support diagnosis if measured within 10-20 min, but not routinely used/reliable

Differentials: syncope (cardiac, vasovagal, orthostatic), psychogenic non-epileptic seizures (PNES), transient ischemic attack, migraine with aura, hypoglycemia, panic attacks, sleep disorders (parasomnias, cataplexy), movement disorders.

General principles:

• Single unprovoked seizure: AED (anti-epileptic drug) not always started immediately: individualized decision based on recurrence risk, patient preference, occupational/driving implications

• AED choice guided by seizure type, syndrome, comorbidities, side effect profile, and (critically) reproductive plans in women of childbearing age

First-line AEDs by seizure type:

• Focal seizures: lamotrigine or levetiracetam (favorable side-effect profiles); carbamazepine also effective (enzyme-inducing, drug interaction considerations)

• Generalized tonic-clonic/generalized epilepsies: sodium valproate historically first line but AVOID in women of childbearing potential due to major teratogenicity (neural tube defects, neurodevelopmental disorders) unless no suitable alternative and pregnancy prevention program in place: levetiracetam or lamotrigine preferred alternatives in this group

• Absence seizures: ethosuximide (first line if absence-only) or sodium valproate; avoid carbamazepine/gabapentin (can worsen absence/myoclonic seizures)

• Myoclonic seizures: sodium valproate (males/non-childbearing), levetiracetam

Typical starting doses (adult, titrate to response/tolerability):

• Levetiracetam: 250–500mg bd, up to 1500mg bd

• Lamotrigine: slow titration essential (Stevens-Johnson syndrome/DRESS risk with rapid titration), start 25mg od, increase gradually over weeks to maintenance 100–200mg bd

• Sodium valproate: 300mg bd, up to 1–2g/day

• Carbamazepine: 100–200mg bd, up to 400mg bd-tds (slow-release preferred); monitor for hyponatremia, requires enzyme-interaction review

Monitoring: clinical response (seizure freedom is the goal, not just reduction), side effects, drug levels only where clinically indicated (not routine for most newer AEDs; useful for phenytoin, carbamazepine, valproate in specific scenarios), adherence.

Status epilepticus (seizure >5 minutes or recurrent seizures without recovery, emergency):

• ABC, oxygen, glucose check (correct hypoglycemia immediately)

• First-line: IV lorazepam 4mg (or diazepam 10mg IV/PR, or buccal midazolam 10mg if no IV access): repeat once after 5–10 min if ongoing

• Second-line (if still seizing after benzodiazepines): IV levetiracetam (60mg/kg, max 4.5g), or valproate (40mg/kg, max 3g), or phenytoin (20mg/kg, with cardiac monitoring)

• Third-line (refractory, 30-60 min): general anesthesia (propofol, thiopental, or midazolam infusion), ICU, EEG monitoring, urgent neurology

• Identify and treat precipitant (infection, non-adherence, alcohol withdrawal, metabolic derangement, structural lesion)

Non-pharmacological: epilepsy surgery (for refractory focal epilepsy with identified resectable focus), vagal nerve stimulation, ketogenic diet (particularly pediatric refractory epilepsy), addressing seizure triggers (sleep deprivation, alcohol, photic stimulation, missed medication)

Lifestyle/safety counseling: driving restrictions (jurisdiction-specific seizure-free periods), water safety (supervised swimming/bathing), occupational hazards, SUDEP (sudden unexpected death in epilepsy) risk discussion, contraception/pregnancy planning (folic acid 5mg preconception, teratogenicity counseling, AED level changes needed in pregnancy).

Referral: neurology for all new-onset epilepsy, treatment-resistant seizures (failure of 2 appropriately chosen/dosed AEDs: consider epilepsy surgery workup), pregnancy planning, diagnostic uncertainty.